Machine for grinding and polishing workpieces

ABSTRACT

Machine for grinding and polishing workpieces having a spherical surface, such as spectacle glasses, optical lenses, and the like, including a workpiece support disposed for rotation about a generally vertical axis for mounting the workpiece for exposure during the machining operation to the action of a work tool operatively applied under pressure against the workpiece for carrying out such action, the workpiece support having a spherical workpiece receiving surface provided with a predetermined radius of curvature generally corresponding to that of the spherical surface of the workpiece to be operatively mounted thereon and situated such that the center of the radius of curvature coincides with the rotation axis of the workpiece support, a work tool holder such as a pressure spindle sleeve for operatively holding the work tool for carrying out the grinding and polishing action and for maintaining the work tool against the workpiece under the applied pressure, a rocker connected to the work tool holder to form a unit therewith and mounted for reciprocating movement about a pivot axis arranged generally normal to the rotation axis of the workpiece support, and a reciprocating drive such as a crank drive for effecting reciprocating movement of the rocker and work tool holder, in which the reciprocating drive is provided with reciprocating means having an invariable or constant operative amplitude of reciprocating movement such as crank arm means having an invariable operative crank radius and corresponding amplitude of crank reciprocating movement, and in which an intermediate selectively variable drive transmission means is further provided.

The present invention relates to a machine for grinding and polishingworkpieces having a spherical surface, such as spectacle glasses,optical lenses or the like, the workpiece or workpieces being mounted ona rotating support for exposure during the machining process to theaction of a tool applied against the workpiece or workpieces underpressure, which tool is held by a pressure spindle sleeve which in turnis fastened to a rocker adapted for reciprocating movement by means of acrank drive, utilizing an intermediate transmission drive means in aselectively adjustable manner and mounted on a rocker pivot axlearranged normal to the axis of rotation of the workpiece support.

German DOS 2,252,502 discloses a machine for grinding and polishinglenses using a rocker which is mounted on an axle and is movable backand forth by means of a motorized crank drive. For the purpose ofadjusting the amplitude of the oscillatory movement of this rocker, themotorized crank drive as a whole is guided linearly movably on themachine frame and is variable in its relative position by means of ahand crank as well as positioning spindle non-rotationally connectedtherewith. Depending on the direction of rotation of the crank, thecrank pin of the crank drive, engaging in the slide-block of a leverarm, undergoes a displacement such that the distance of the crank pinfrom the pivot axle of the rocker is correspondingly increased orreduced.

A disadvantage of this known crank drive arrangement lies in the factthat, due to the direct action of the crank pin on the slide-block armof the rocker, distortions of the sine configuration having anunfavorable effect on the movement conditions of the rocker, i.e.different angular velocities, occur in the reciprocating movement of therocker. Such disadvantageous effects on the performance are the morepronounced, the closer the crank pin is brought to the pivot axle. Forthis reason alone, machines which are equipped with a rocker drive ofthe above described type are clearly unsuitable for the machining ofworkpieces or lenses having a strong or more pronounced radius ofcurvature, in particular those which, as is known, require an adjustmentof the rocker in the vicinity of the set value zero or zero amplitude ofrocker oscillation.

It is among the objects and advantages of the present invention to avoidthe above discussed disadvantages of such known type rocker drive, andto provide an improved rocker drive, developed and perfected in such away that it is able, as in the form of a relatively simple construction,to fulfill the requirements for achieving substantially more exact workresults in connection with the grinding and polishing of workpieces,e.g. spectacle lenses, and furthermore is distinguished by a mode ofoperation easily adaptable to the conditions of use.

It is among the further objects and advantages of the invention toprovide the corresponding machine equipped with such improved rockerdrive in form and manner that even operators who have had little or noexperience with this kind of machine will be able to carry outtherewith, more or less automatically, exactly reproducible adjustmentprocesses exclusively in accordance with given values, for accomplishingthe desired grinding and polishing of workpieces, such as spectacle oreyeglass lenses or the like, with minimum chance of error.

Other and further objects and advantages of the present invention willbecome apparent from a study of the within specification andaccompanying drawings, in which:

FIG. 1 is an overall schematic perspective view of an embodiment of thebasic machine for the machining of workpieces having a spherical surfaceusable according to the present invention;

FIG. 2 is a schematic view of the embodiment of FIG. 1 which shows indetail the rocker drive of the machine, indicating in phantom a carriagecarrying the most important structural elements of the rocker drivesystem and guided for movement at the machine frame of the basicmachine, and further indicating the workpiece and tool elements inlaterally offset relation for clarity of illustration; and

FIG. 3 is a schematic side view, in the direction of the arrows 3--3indicated in FIG. 2, of the arrangement and suspension of the threadedspindle associated with the crank drive of the rocker system.

According to the present invention, a machine for grinding and polishingworkpieces having a spherical surface, such as spectacle glasses,optical lenses, and the like is provided in which an intermediate drivevariable with respect to its transmission ratio is arranged between therocker, holding the work tool for action against the workpiece, and apreferably invariably constant operative amplitude reciprocating drive,e.g. crank drive. In this way, it has been possible to eliminateeffectively all those unfavorable influences which heretofore resultedin distortions of the sine configuration during the oscillatory movementof the rocker and which had a disadvantageous effect on the desiredperformance.

More specifically, by way of the present invention, it is now possibleto establish uniformity of the kinematic movement conditions of therocker to such a degree that angular velocities are obtained withoutappreciable deviations during motion in both directions. Further, therocker drive according to the present invention particularly permits themachining as well of workpieces whose machinable surfaces have a strongradius of curvature and consequently require rocker adjustments whichmay be close to the set value zero.

A preferred embodiment of the intermediate drive according to theinvention is provided in the form of an adjustable transmission linkage,designed as a four-joint drive, selectively variable in its operativetransmission geometric dimensions. With such an intermediate drive,especially favorable kinematic conditions can be obtained by makingvariable the interconnection between the rocker and reciprocating drive,e.g. the active lever arm of the input rocker in drive connection withthe crank gear of the constant and invariable amplitude crank drive. Anarrangement advantageously simple in construction and safe in operationcan be obtained in this regard according to the invention by providing athreaded spindle with a follower nut for varying the operative lineardimension of the active lever arm of the input rocker.

To create the design conditions for favorable and simple adjusting ofthe central position of oscillation or operative midpoint of the rockercarrying the work tool holder, e.g. the pressure spindle sleeve, acoupling rod serves to bring the intermediate drive into drivingconnection with the tool-guiding rocker, and the rocker itself is madeof two parts. One of the rocker parts is the part carrying the pressurespindle sleeve and the other is a part variable in its relativeadjustment to the first part, e.g. by means of a positioning driveacting on the first rocker part, with the force from the crank driveacting via the intermediate drive on the second rocker part.

An adjustability means, simple in design and therefore having afavorable cost effect on the overall conception of the machine, isprovided according to the invention by including a worm gear for varyingthe relative position, e.g. angular disposition about the rocker pivotaxis, of the one part of the rocker carrying the pressure spindle sleevewith respect to the other part connected with the intermediate drive.

The set-up time for adaptation of the center of oscillation, i.e. of theheight of the axis of the pivot of the rocker arm, to the center ofcurvature of the lens radius, i.e. as mounted on the rotatable workpiecesupport, can be greatly shortened according to the invention in a simplemanner in that the constant and invariable oscillating amplitude crankdrive, the selectively variable transmission ratio intermediate driveand the worm gear serving to adjust the two-part rocker are arranged ona common carriage, which is movably guided relative to the machine frameand variable in its relative position or height by means of aheight-controlling spindle gear.

For the same purpose, namely to shorten the set-up time considerably,motor means may be provided for effecting the selective adjustment ofthe transmission ratio linkage of the intermediate drive, for operatingthe worm gear for selective angular adjustment of the two-part rocker,and for energizing the spindle gear for selective height adjustment ofthe common carriage.

Faulty operation in adjusting the various pertinent oscillationparameters of the machine can be particularly avoided in a simple manneraccording to the invention, such as by providing a pointer on one of theparts forming the rocker and a scale on the other rocker part adjustablerelative thereto, to indicate visually the "oscillation position" orrelative adjusted angular position about the rocker pivot axis of bothparts, and in turn by providing a finger formed on this scale support onthe other rocker part, cooperating with a fixed scale, e.g. on themachine frame, to indicate visually the "oscillation amplitude" or drivetransmission ratio. Additionally, by arranging a linear scale secured onthe machine frame to which a pointer movable with the common carriage iscorrelated to indicate visually the "radii range" or relative positionof the axis of pivot of the rocker to the center of curvature of thelens radius as mounted on the rotatable workpiece support, likeavoidance of faulty operation is attainable in this aspect as well.

In order that the indicia of these oscillation parameters to be adjustedcan be plainly seen, according to a further advantageous feature of theinvention, all such scales and conjoint indicator elements are broughttogether at one observable location readily visible from the normallocation of the operator at the machine.

Referring to the drawings, and particularly to FIG. 1, a frame 1 of amachine for grinding and polishing spectacle or eye-glass lenses or thelike having a spherical surface is shown, containing the usual rotatingwork spindle 2, carrying the support 3 which is adapted to receive forrotation therewith several workpieces 4 or blanks. The work spindle 2 isdisposed in the normal manner in a vat 1a or recess formed on themachine frame and which suitably serves, as is known, to catch thepolishing and/or cooling liquid supplied to work station A by means of aconventional system (not shown).

As can further be seen from FIG. 1, a tool holder, including forinstance a tool spindle 5 and a cooperating pneumatic pressure cylinder6, is provided. Specifically, tool spindle 5, designed as a pressurespindle sleeve, is disposed for axially aligned positioning with respectto the work spindle 2. Spindle 5 is guided for axial displacement in thecooperating pneumatic pressure cylinder 6 and acts under axial resilientor spring pressure in known manner via its lower end on the grinding orpolishing tool 7, which in turn is applied onto the workpiece orworkpieces to be machined. Cylinder 6, receiving the pressure spindlesleeve 5, is held by a support arm 8 secured on a rocker 9, and theseparts form a common unit capable of simultaneous rocking oscillation.

As can be seen from FIG. 2, rocker 9 is fixedly mounted on a horizontalpivot axle 10 or bearing shaft. Accordingly, rocker 9 executesoscillating movements about the pivot axis of axle 10 during theoperative process, so that spindle sleeve 5 and hence the tool 7 whichis continuously applied under pressure against the workpieces 4correspondingly undergo a continual variation of their relative positionwith respect to spindle 2.

For greater clarity, spindle sleeve 5 and spindle 2 are shown in FIG. 2in laterally offset relation to the rocker 9, and the support arm 8 ismerely indicated schemetically by two dash-dot lines with correspondingconnecting points B, C, and B', C', respectively. Actually, points B'and C' of cylinder 6 lie in a plane which is normal to the plane of thepaper regarding FIG. 2 and which intersects points B and C of rocker 9as is more clearly shown in the orientation of these parts in FIG. 1.

The pivot axle 10 of rocker 9 is mounted rotatably, e.g. in journals(not shown), on a separate common carriage 11, indicated in phantom inFIG. 2, and such common carriage is selectively adjustable in heightrelative to the machine frame 1 by means of appropriate sliding orroller guides 12. This measure is necessary to be able to bring theheight adjustment of axle 10 into desirable coincidence with the centerM of the radius of curvature r of the respective spherical workpiecesupport 3 used in the operative process, such elements also being shownin laterally offset relation in FIG. 2 for greater clarity. Depending onthe magnitude of the radius r, the axle 10 of rocker 9 must be moved upor down until the center M of the radius of curvature r of the workpiecesupport 3 and the ideal horizontal axis of the pivot pin or axle 10 havereached an exact uniform, e.g. vertical, level.

It will be seen that the axis of rotation of the rotating spindle 2 andsupport 3 in effect lies in one plane, e.g. a first vertical plane, andthat the pivot axis of pivot axle 10 of rocker 9 correspondingly lies inanother plane, e.g. a second vertical plane, and that the second planeis parallel to and disposed at a fixed distance from the first plane, inany position of movement of the carriage 11. Thus, while axle 10 ofrocker 9 may be moved up or down relative to center M for the desiredpurposes, the pivot axis thereof will always remain in the second planein constantly spaced relation to the axis of rotation of the spindle 2and support 3.

In order to drive rocker 9, a reciprocating drive is used having aconstant operative amplitude of reciprocating movement. This may beprovided in the form of a crank drive known per se, for instanceconsisting of a motor 13, a crank sheave or member 14 mounted on theoutput shaft of the corresponding motor drive, and a connecting rod 16pivotally hinged at one end to a stationary crank pin 15. Crank pin 15is fixed on crank member 14 to provide an invariable or constant crankradius and corresponding amplitude of reciprocating movement. The otheror outward free end of the connecting rod 16 pivotally engages via afloating pivot the freely movable end of a lever 17.

Lever 17 is rotationally mounted via a fixed pivot on the trunnion 18 ofa bearing block 19 disposed on the common carriage 11. Lever 17 belongsto an intermediate drive or first positioning drive, whose othercomponent parts include a threaded spindle 20 rotatably mounted on suchlever 17, a traveling or follower spindle nut 21, a first geared motor22 serving to drive spindle 20, and a coupling rod 23 articulatedlyconnected at the one or lower end thereof with the spindle nut 21 via atraveling pivot thereat. Coupling rod 23 articulatedly engages at theother or upper end thereof with a lever arm 24 rotatably mounted on axle10. Coupling rod 23 thus provides for an invariable or constant lineardistance between its articulation axis at spindle nut 21 and itarticulation axis at lever arm 24.

Between this intermediate drive, formed advantageously in the manner ofa four-joint drive, e.g. as a selectively adjustable transmission ratiosecond class lever linkage system, there is a form-locking connectionwith rocker 9, to which end a support plate 26 rigidly connected withlever arm 24 situated in carriage 11 has placed on it a further orsecond geared motor 27, the output shaft 28 of which, preferablydesigned as a worm shaft provided with worm 28a, is in operativeengagement with a serration 9a correspondingly designed on rocker 9 andforming a worm wheel for coaction with worm 28a.

While by means of this resultant further or second intermediatepositioning drive of worm gear 9a, 28a the basic adjustment of therocker 9 can be selectively varied, i.e. the relative angular positionof rocker 9 with respect to the work spindle 2 can be selectivelyvaried, the above described intermediate drive or first positioningdrive serves to fix selectively the lever ratios determining theamplitude of oscillation of rocker 9, or more specifically the activepoint of engagement of the coupling rod 23 on the threaded spindle 20via traveling spindle nut 21. There is also a certain functionalinterdependence between the two positioning drives inasmuch as eachvariation of the lever ratio, i.e. selective reduction or increase ofthe lever portion or lever arm a, which is defined by the distancebetween the axis of trunnion 18 and the point at which spindle nut 21 isdisposed along drive spindle 20, is accompanied by a variation--if evena slight one--of the previous center position of rocker 9, due to theconstant dimension of the linkage of coupling rod 23 between spindle nut21 and lever arm 24, into which the rocker 9 can be suitably returned bymeans of the motorized worm gear 9a, 28a. While such worm gear serves torotate rocker part 9 and axle 10 relative to carriage 11 for thisadjustment, rocker lever arm part 24 and motor 27 on plate 26 remain inposition relative to carriage 11 during this time since these lattercomponents are rotatably freely suspended on axle 10 under the controlof coupling rod 23.

The set position or "oscillation position" of rocker 9 relative to theactuating lever arm 24 obtainable with the worm gear 9a, 28a can bereadily visually indicated by means of a pointer arm 30 fastened on therocker. The pointer arm 30 is conveniently associated with a scale arc31a, having appropriate reference markings, which in turn is provided ona plate 31 rigidly connected with the actuating lever 24. A finger 32 isformed on this plate 31, and due to the form-locking connection betweenlever 24 and rocker 9 by the worm gear 9a, 28a, such finger 32 alwaysparticipates in the oscillatory movements of rocker 9. Thus, the"oscillation amplitude" of rocker 9 can also be suitably made visible tothe operator on a scale 34a l associated with finger 32. Scale 34ahaving indicia corresponding to pertinent angle divisions is applied ona plate 34 fastened on carriage 11.

With regard to the height adjustment of carriage 11, for this purpose,i.e. for moving the carriage up and down, a positioning spindle 37drivable by means of a still further or third geared motor 36, e.g.mounted on machine frame, advantageously is provided. The verticalspindle 37 engages in a correspondingly threaded positioning block 38,which in turn is fastened to the carriage 11. To indicate the heightposition of carriage 11, a ruler 40 may be provided which is rigidlyassociated with the carriage 11 and on which a linear scale 40a isformed, whereby the corresponding axle 10--center of radius of curvatureM "radii range" adjustment movement or the set poosition reached canlikewise be suitably read with the aid of a cooperating line mark member41 on the machine frame 1.

As is evident in particular from FIG. 1, a control box 44 having acontrol panel, containing the most important buttons necessry to operatethe machine with appropriately labelled designations, is convenientlyarranged by means of a prop or leg 43 near the location of the abovedescribed observable scale arrangements. Thus, for the purpose ofadjusting the so-called "Radii Range," i.e. for achieving coincidence ofthe axis of axle 10 and center M, two alternately operate switch buttons45a and 45b are provided, by the actuation of which motor 36 is set incorresponding forward and reverse rotational motion. Depending on whichof the buttons 45a, 45b is pressed, motor 36, and of course the spindle37 driven by it, will execute rotational movements in one or the otherappropriate rotational direction. Analogously, the additional buttons46a and 46b which also are to be pushed, serve to adjust the optimum"Oscillation Position" of rocker 9, i.e. the angle of offset betweenparts 9 and 24 on axle 10. As one or the other button 46a, 46b ispressed, worm shaft 28, and in turn worm 28a will be driven by motor 27in one or the other appropriate direction of rotation to accomplish thedesired angular adjustment. The "Oscillation Amplitude" adjustment forvarying the drive transmission ratio takes place likewise by actuationof one of the switch buttons 47a, 47b, whereby motor 22 is set inappropriate motion. While by actuation of button 47a the spindle 20 isdriven in a direction resulting in a reduction of the lever arm a, onthe other hand by actuation of the other button 47b the spindle 20 isdriven in the opposite direction, whereby the lever arm a is increasedwith respect to the distance of the point of engagement of connectingrod 23 from the pivot point or trunnion 18.

All switch buttons of the above described control parameters aresuitable designed in the conventional manner so that the geared motorenergized by the actuation of a corresponding button remains energizedin the appropriate rotational direction until the finger pressure isremoved from the button.

Since according to the embodiment shown in FIG. 2 and 3, the threadedspindle 20 passes by the bearing block 19 laterally, it isadvantageously possible upon actuation of the respective buttonassociated with the "Oscillation Amplitude" adjustment feature to reducethe active lever arm a at lever 17 to such an extent that at the end ofthe positioning movement for rocker 9 there results an amplitude of thevalue "zero". This can be achieved by bringing the spindle nut 21 up toand axially coincidental with the fixed pivot point or trunnion 18 oflever 18. The maximum amplitude of oscillation of rocker 9 occurs, onthe other hand, when spindle nut 21 occupies a relative position to thefixed pivot point or trunnion 18 having the greatest lever distance afrom pivot point 18 of lever 17.

It will be appreciated, therefore, that in accordance with the presentinvention a machine for grinding and polishing workpieces having aspherical surface, such as spectacle glasses or eyeglasses, opticallenses, and the like, of the foregoing type is advantageously providedin which the reciprocating drive for the rocker and work tool holderincludes reciprocating means having an invariably constant operativeamplitude of reciprocating movement and in which in conjunctiontherewith an intermediate selectively variable drive transmission meansis provided with operatively interconnects the constant amplitudereciprocating means of the reciprocating drive with the rocker and whichhas a variable operative drive transmission ratio for selectiveadjustment of the amplitude of reciprocating movement of the rocker andwork tool holder.

In this way, during rotation of the workpiece support and work toolaction under rocker oscillation, distortions of the sine configurationhaving an unfavorable effect on the movement conditions of the rockerwill be significantly avoided. In particular, such distortions at thecorrespondingly different angular velocities encountered will not occureven when the rocker oscillation amplitude is required to be adjusted inthe vicinity of the set value zero or zero oscillation amplitude rangeas in the case of workpieces having a strong or pronounced radius ofcurvature, i.e. where the radius r is relatively short for example ascompared with the operative maximum oscillation amplitude of thereciprocating means, or that of the invariably constant crank radius, astransmitted.

Preferably, the intermediate drive transmission means is provided in theform of an adjustable drive transmission linkage having an operativeadjustment range selectively varying from a maximum amplitude ofreciprocating movement as determined by the corresponding invariablyconstant operative amplitude of the reciprocating means of thereciprocating drive to an approximately zero amplitude of reciprocatingmovement. The drive transmission linkage may be suitably constructed asa simple, sturdy and precisely functioning four-joint linkage drivecorrespondingly variable in its operative transmission geometricdimensions, e.g. a linkage lever system.

More particularly, such lever system may contain an input rocker leverpivotally mounted at a first point thereon on a fixed pivot andpivotally connected at a second point thereon linearly spaced from thefirst point and from the fixed pivot to the reciprocating means or crankarm means for driven reciprocating movement in accordance with fixedcharacteristics of the crank drive, attachment means operativelydisposed for selectively adjustable movement along a lever arm pathhaving a range extending from the first point on the lever at the fixedpivot to a further point on the lever linearly spaced from the firstpoint and remote from the fixed point, and a connecting rod operativelypivotally connected at a proximate pivotal point thereon to theattachment means and at a distal pivotal point thereon to the rocker.

Selective adjustment of the amplitude of reciprocating movement asimparted to the rocker at the distal pivotal point may thereby beadvantageously carried out from a maximum amplitude determined by thecorresponding amplitude of the reciprocating means or crank arm means,e.g. invariably constant crank radius of the crank drive, when theattachment means is moved to the further point, e.g. the second point inthe case of a second class lever system, on the lever remote from thefixed pivot to an approximately zero amplitude when the attachment meansis moved to the first point on the lever and the proximate pivotal pointof the connecting rod and the fixed pivot are in approximate operativecoincidence.

Generally, the four-joint drive may comprise a pivotally mounted inputrocker lever in drive connection with the reciprocating means or crankarm means of the crank arm drive and having an active lever arm portiona, and output linkage varying means operatively connected between theinput rocker lever and the rocker and adjustably disposable with respectto the active lever arm portion of the input rocker lever whereby tovary the magnitude of the corresponding active lever arm thereof and inturn the transmission ratio of the intermediate drive means. Suitably,such output linkage varying means may comprise attachment means, forinstance including a threaded spindle rotatably disposed on the inputrocker lever along the active lever arm portion thereof and a travelingfollower nut operatively disposed on the threaded spindle for varyingthe magnitude of the active lever arm. Output linkage means in turn maybe provided on the attachment means for operative connection to therocker, for instance including a coupling rod or connecting rodpivotally connected to the follower nut for transmitting the force ofthe reciprocating drive or crank drive via the input rocker lever andthreaded spindle to the rocker in dependence upon the position of thefollower nut.

Selective variable intermediate positioning drive transmission means arealso desirably contemplated in association with the rocker foroperatively interconnecting the intermediate drive transmission means orlinkage lever system with the rocker under selective compensatingadjustment of the angular positional orientation of the mid-point of theamplitude of reciprocating movement, e.g. with respect to a referenceplane intersecting the pivot axis of the rocker, in correspondingrelation to the drive transmission ratio selected for the intermediatedrive transmission means or linkage lever system. Thus, the rocker maybe formed of a pair of separate rocker parts mounted for reciprocatingmovement together about the rocker pivot axis, including a first rockerpart carrying the work tool holder or pressure spindle sleeve and asecond rocker part variable in its relative adjustment position to thefirst rocker part and operatively connected to the output linkage meansor coupling or connecting rod of the four-joint linkage drive at a pointon such rod spaced from the pivotal connection thereof to the attachmentmeans or follower nut, whereby the intermediate positioning drivetransmission means may adjust the relative disposition between the twoseparate rocker parts. In particular, the intermediate positioning drivemeans may advantageously comprise a worm gear operativelyinterconnecting the two rocker parts for relative angular displacementtherebetween about the axis of pivot of the rocker.

Preferably, an arrangement is contemplated wherein the rocker includes afirst support part connected to the pressure spindle sleeve and a secondoffset arm part, i.e. offset relative to the first support part aboutthe rocker axis of pivot, to which the distal pivotal point of thecoupling or connecting rod of the four-joint drive linkage is pivotallyconnected, with said rocker parts being mounted for reciprocatingmovement together about the rocker axis of pivot and for relativerotational positioning movement with respect to each other about suchaxis of pivot. In this way, the selectively variable positioning meansmay selectively control the relative rotational positioning movementbetween the two rocker parts and thereby compensate for changes in thedrive transmission ratio in dependence upon the position of theattachment means or follower nut along its lever movement path. Byreason of the inclusion of a simple, sturdy and precisely functioningworm gear means at the operative interconnection of the two rocker partson the common rocker shaft, the rocker support part may be convenientlyrotationally moved relative to the rocker offset arm part, i.e. tochange the angle of offset therebetween about the rocker axis of pivot.

The selectively adjustable carrier means and spindle gear operativelyconnected thereto for varying the vertical position thereof relative tothe machine portion containing the workpiece support, advantageouslypermit displacement together of the two rocker parts, the reciprocatingmeans or crank drive, the intermediate drive transmission means orlinkage lever system and the selectively variable intermediatepositioning means or worm gear means, in relation to the workpiecesupport to bring the work tool holder or pressure spindle sleeve intooperative position for the work tool to be applied against theworkpiece. Additionally, the presence of the appropriately locatedvisual indicating means advantageously permit readily observable preciseindication of the relative angular position about the pivot axis of therocker as between the two rocker parts, the drive transmission ratio andcorresponding amplitude of common reciprocating movement of the rockerparts in dependence upon the position of the attachment means orfollower nut along the lever arm movement path thereof, and the relativeposition of displacement between the carrier means or carriage means andthe workpiece support and in turn of the relative levels of the centerof the radius of curvature of the workpiece support and the axis ofpivot of the rocker.

Accordingly, by reason of the foregoing constructional features of thepresent invention, a simple, sturdy, safe and readily adaptable systemis provided for repeatedly achieving exact and uniform work results evenby operators having little or no experience with the type of machine inquestion, and permitting exactly reproducible selective adjustment ofthe appropriate parameters exclusively in accordance with appropriategiven values, e.g. of "radii range," "oscillation position" and"oscillation amplitude," as noted above, regardless of the skill of theoperator and more or less automatically.

It will be appreciated that the instant specification and drawings areset forth by way of illustration and not limitation, and that variousmodifications and changes may be made therein without departing from thespirit and scope of the present invention which is to be limited solelyby the scope of the appended claims.

What is claimed is:
 1. Machine for grinding and polishing workpieceshaving a spherical surface, such as spectacle glasses, lenses, and thelike, including a workpiece support disposed for rotation about an axisfor mounting the workpiece for exposure during the machining operationto the action of a work tool applied under pressure against theworkpiece, a pressure spindle sleeve for holding the work tool forcarrying out such action, a rocker connected to the pressure spindlesleeve and mounted for reciprocating movement about an axis of pivotarranged normal to the axis of rotation of the workpiece support, therotation axis of the workpiece support lying in a first plane and thepivot axis of the rocker lying in a second plane parallel to anddisposed at a fixed distance from the first plane, and a crank drive foreffecting reciprocating movement of the rocker and in turn of thepressure spindle sleeve, in which the crank drive is provided with crankarm means having an invariable operative crank radius and in which anintermediate drive means is disposed operatively between the crank armmeans of the crank drive and the rocker which has a variable operativedrive transmission ratio for selective adjustment of the reciprocatingmovement of the rocker and pressure spindle sleeve.
 2. Machine accordingto claim 1 wherein the intermediate drive means is provided as afour-joint linkage drive which is correspondingly variable in itsoperative transmission geometric dimensions.
 3. Machine according toclaim 2 wherein the four-joint drive includes a pivotally mounted inputrocker lever in drive connection with the crank arm means of the crankdrive and having an active lever arm portion, and output linkage varyingmeans operatively connected between the input rocker lever and therocker and adjustably disposable with respect to the active lever armportion of the input rocker lever to vary the magnitude of thecorresponding active lever arm thereof and in turn the transmissionratio of the intermediate drive means.
 4. Machine according to claim 3wherein the output linkage varying means include a threaded spindlerotatably disposed on the input rocker lever along the active lever armportion thereof, and a traveling follower nut operatively disposed onthe threaded spindle for varying the magnitude of such active lever armand having output linkage means thereon for operative connection to therocker.
 5. Machine according to claim 4 wherein such output linkagemeans include a coupling rod pivotally connected to the follower nut fortransmitting the force of the crank drive via the input rocker lever andthreaded spindle to the rocker in dependence upon the position of thefollower nut, and the rocker includes a first rocker part carrying thepressure spindle sleeve and a second rocker part variable in itsrelative adjustment position to the first rocker part and operativelyconnected to the coupling rod at a point on such rod spaced from thepivotal connection to the follower nut, and wherein intermediatepositioning drive means are provided in association with the rocker foradjusting the relative dispositions between the first rocker part andthe second rocker part.
 6. Machine according to claim 5 wherein theintermediate positioning drive means include a worm gear operativelyinterconnecting the first rocker part and the second rocker part forrelative angular displacement therebetween about the axis of pivot ofthe rocker.
 7. Machine according to claim 6 wherein the first and secondplanes are vertical planes, common carriage means are provided which arepositioned for guided vertical movement relative to the machine portioncontaining the workpiece support and on which the crank drive, theintermedite drive means, and the rocker parts including the intermediatepositioning drive means are commonly carried, and a spindle gearoperatively connected to the carriage means for varying selectively thevertical position thereof relative to the machine portion and in turnthe level of the height of the rocker relative to the workpiece supportand the vertical disposition of the pivot axis in the second planerelative to the rotation axis in the first plane.
 8. Machine accordingto claim 7 wherein motor means are provided for correspondinglyselectively rotating the threaded spindle of the intermediate drive, theworm gear of the intermediate positioning drive means and the spindlegear of the carriage means.
 9. Machine according to claim 8 wherein apointer is provided on one of the rocker parts and a scale supporthaving a cooperating rocker scale in alignment with such pointer anddisplaceable with respect thereto is provided on the other of the rockerparts for indicating the selected angular relation between the tworocker parts, and a finger is formed on the scale support whichcooperates with a stationary angular scale on the carriage means forindicating the selected oscillation amplitude of the rocker about theaxis of pivot of the rocker, and wherein a linear scale moveable withthe carriage means is associated with a stationary further paintersecured to the machine portion containing the workpiece support forindicating the selective position of the carriage means relative to suchmachine portion.
 10. Machine according to claim 9 wherein the rockerscale, stationary angular scale and stationary linear scale are arrangedtogether at one observable location readily visible to the operator ofthe machine.
 11. Machine for grinding and polishing workpieces having aspherical surface, such as spectacle glasses, lenses, and the like,which comprisesa workpiece support disposed for rotation about an axisfor mounting the workpiece for exposure during the machining operationto the action of a work tool operatively applied against the workpiece,a work tool holder for operatively holding the work tool for carryingout such action, a rocker connected to the work tool holder to form aunit therewith and mounted for reciprocating movement about an axis ofpivot arranged normal to the axis of rotation of the workpiece support,the rotation axis of the workpiece support lying in a first plane andthe pivot axis of the rocker lying in a second plane parallel to anddisposed at a fixed distance from the first plane, a reciprocating drivefor effecting reciprocating movement of the rocker and work tool holderand including a reciprocating means having a constant operativeamplitude of reciprocating movement, and an intermediate selectivelyvariable drive transmission means operatively interconnecting theconstant amplitude reciprocating means of the reciprocating drive withthe rocker and having a variable operative drive transmission ratio forselective adjustment of the amplitude of reciprocating movement of therocker and work tool holder.
 12. Machine according to claim 11 whereinthe intermediate drive transmission means includes an adjustable drivetransmission linkage having an operative adjustment range selectivelyvarying from a maximum amplitude of reciprocating movement determined bythe corresponding constant operative amplitude of the reciprocatingmeans of the reciprocating drive to an approximately zero amplitude ofreciprocating movement.
 13. Machine according to claim 11 whereinselectively variable positioning drive transmission means are providedin association with the rocker for operatively interconnecting theintermediate drive transmission means with the rocker under selectivecompensating adjustment of the angular positional orientation of themid-point of the amplitude of reciprocating movement of the rocker withrespect to a reference plane intersecting the pivot axis of the rockerin relation to the drive transmission ratio selected for theintermediate drive transmission means.
 14. Machine according to claim 11wherein selectively adjustable carrier means are provided for displacingthe rocker, reciprocating means and intermediate drive transmissionmeans in relation to the workpiece support to bring the work tool holderinto operative position for the work tool to be applied against theworkpiece while correspondingly displacing the pivot axis of the rockerwithin the second plane.
 15. Machine for grinding and polishingworkpieces having a spherical surface, such as spectacle glasses,lenses, and the like, which comprisesa work tool, a workpiece supportdisposed for rotation about an axis for mounting the workpiece forexposure during the machining operation to the action of the work tooloperatively applied against the workpiece, said workpiece support havinga spherical workpiece receiving surface provided with a predeterminedradius of curvature corresponding to that of the spherical surface ofthe workpiece to be operatively mounted thereon and situated such thatthe center of such radius of curvature coincides with the rotation axisof the workpiece support, a work tool holder including a pressurespindle sleeve for operatively holding the work tool for carrying outsuch action and for maintaining the work tool against the workpieceunder operatively applied pressure, a rocker connected to the work toolholder to form a unit with the pressure spindle sleeve and mounted forreciprocating movement about an axis of pivot arranged normal to therotation axis, the rotation axis of the workpiece support lying in afirst plane and the pivot axis of the rocker lying in a second planeparallel to and disposed at a fixed distance from the first plane, areciprocating drive including a crank drive for effecting reciprocatingmovement of the rocker and pressure spindle sleeve and further includinga reciprocating crank arms means having an invariably constant operativecrank radius and corresponding amplitude of crank reciprocatingmovement, and an intermediate selectively variable drive transmissionmeans operatively interconnecting the crank arm means and the rocker andhaving a variable operative drive transmission ratio for selectiveadjustment of the amplitude of the reciprocating movement of the rockerand pressure spindle sleeve, said intermediate drive transmission meansbeing arranged for variation during reciprocating movement of the rockerby the crank drive and including an adjustable drive transmissionlinkage having an operative adjustment range selectively varying from amaximum amplitude of reciprocating movement determined by thecorresponding constant operative amplitude of the crank radius to anapproximately zero amplitude of reciprocating movement.
 16. Machineaccording to claim 15 wherein the intermediate drive transmissionlinkage includes a lever operatively pivotally mounted at a first pointthereon on a fixed pivot and operatively pivotally connected at a secondpoint thereon linearly spaced from the first point and from the fixedpivot point to the crank arm means for reciprocating movement inaccordance with the crank drive, attachment means operatively disposedfor selectively adjustable movement along a lever arm path having arange extending from the first point on the lever at the fixed pivot toa further point on the lever linearly spaced from the first point andremote from the fixed pivot, and a connecting rod operatively pivotallyconnected at a proximate pivotal point thereon to the attachment meansand at a distal pivotal point thereon to the rocker, for selectivelyadjusting the amplitude of reciprocating movement imparted to the rockerat the distal pivotal point from a maximum amplitude determined by thecorresponding amplitude of the constant crank radius of the crank drivewhen the attachment means is moved to the further point on the leverremote from the fixed pivot to an approximately zero amplitude when theattachment means is moved to the first point on the lever and theproximate pivotal point of the connecting rod and the fixed pivot are inapproximate operative coincidence.
 17. Machine according to claim 16wherein the rocker includes a first support part connected to thepressure spindle sleeve and a second offset arm part to which the distalpivotal point of the connecting rod is pivotally connected, said rockerparts being mounted for reciprocating movement together about the axisof pivot of the rocker and for relative rotational positioning movementwith respect to each other about such axis of pivot, and selectivelyvariable positioning means are provided in association with the rockerfor selectively controlling the relative rotational positioning movementbetween said rocker parts and in turn for selective compensatingadjustment of the angular positional orientation of the mid-point of theamplitude of reciprocating movement of the rocker support part, withrespect to a reference plane intersecting the pivot axis of the rocker,in corresponding relation to the drive transmission ratio selected forthe intermediate drive transmission means and in correspondingdependence upon the position of the attachment means along the movementpath thereof.
 18. Machine according to claim 17 wherein the selectivelyvariable positioning means include worm gear means for selectivelyrotationally moving the rocker support part relative to the rockeroffset arm part.
 19. Machine according to claim 18 wherein selectivelyadjustable carrier means are provided for displacing together the rockerparts, crank drive, intermediate transmission linkage and worm gearmeans in relation to the workpiece support to bring the pressure spindlesleeve into operative position for the work tool to be applied againstthe workpiece.
 20. Machine according to claim 19 wherein observableindicating means are provided for indicating the relative angularposition about the pivot axis between the rocker support part and rockeroffset arm part, the drive transmission ratio and correspondingamplitude of reciprocating movement of the rocker parts in dependenceupon the position of the attachment means along the movement paththereof, and the relative position of displacement between the carriermeans and the workpiece support and in turn of the relative levels ofthe center of the radius of curvature of the workpiece support and theaxis of pivot of the rocker.